1. Field of the Invention
The present invention relates to a method for cooking food material of varying volume, such as water and rice in a cooking apparatus.
2. Description of the Prior Art
In a cooking device such as an electric rice cooker, and particularly in an electric rice cooker capable of cooking rice by a timer operation, a cooking control circuit having a clock function is provided. The cooking control circuit in recent electric rice cookers has included a microcomputer which is capable of performing the clock function and other various controls in the cooking operation. When a user sets a desired cooking completion time into the cooking control circuit, the cooking control circuit calculates a timer operation running period from the present time to the desired cooking completion time. The cooking control circuit then subtracts the period required for the cooking operation, that is, a specified cooking operation period set previously in the cooking control circuit, from the timer operation running period. This calculates a time for starting the cooking operation. As a result, the cooking operation starts at the calculated cooking operation starting time, and finishes at the desired cooking completion time.
It is well known that in an electric rice cooker, the cooking operation period varies in relation to the amount or volume of food material to be cooked, i.e., volume of water and rice, which are contained together in the electric rice cooker. That is, the cooking operation period takes longer when the volume of the food material is greater. However, the electric rice cooker as described above has no function for measuring the volume of food material to be cooked. Therefore, the cooking operation period typically is determined uniformly based on the maximum capacity of the electric rice cooker, and this value is stored in the cooking control circuit. However, when the volume of the food material to be cooked is less than the maximum capacity of the electric rice cooker, for example, when the volume of food material to be cooked is in the small or medium capacity range of the electric rice cooker, the correct cooking operation period is shorter than this stored cooking operation period. As a result, when setting a desired cooking completion time for cooking a volume of food material in the small or medium capacity range, the cooking operation finishes before the desired cooking completion time. This is because the cooking start time is determined by the stored cooking operation period, which is determined by the maximum capacity of the electric rice cooker. In other words, the desired cooking completion time is later than the time when the actual cooking operation is completed.
It is also known that in an electric rice cooker, the cooking operation period varies in relation to the ambient temperature or the temperature of the food material to be cooked, i.e., water and rice, before the cooking operation starts. That is, the cooking operation period takes longer when the initial temperature of the food material to be cooked is relatively low. This occurs, for example, in winter. However, the electric rice cooker as described above has no capability to adjust the cooking operation period in accordance with the temperature of the food material to be cooked before starting the cooking operation.
Such circumstances also apply to the measurement of volumes of various other food materials to be cooked, such as soybeans, etc.